Toner with increased amount of surface additives and increased surface additive adhesion

ABSTRACT

A toner and process for making the toner wherein each combined resin and colorant particle has an average size less than about 10 microns and wherein the surface additive particles averaging less than about 40 nanometers in size average greater than two (2) percent of the combined weight of resin and colorant in the toner and wherein the Additive Adhesion Force Distribution percent value after 12 kilojoules of energy is greater than 40 percent.

CROSS-REFERENCE TO COPENDING APPLICATIONS

This application is based on a Provisional Patent Application No.60/258,271, filed Dec. 27, 2000.

Attention is directed to commonly owned and assigned copendingApplications Nos.: U.S. Ser. No. 09/748,920, filed Dec. 27, 2000entitled “BLENDING TOOL WITH AN ENLARGED COLLISION SURFACE FOR INCREASEDBLEND INTENSITY AND METHOD OF BLENDING TONERS” and U.S. Ser. No.09/749,059, filed Dec. 27, 2000 entitled “BLENDING TOOL WITH ANADJUSTABLE COLLISION PROFILE AND METHOD OF ADJUSTING THE COLLISIONPROFILE”.

BACKGROUND OF THE INVENTION

The field of the proposed invention relates to high intensity blendingapparatus and processes, particularly for blending operations designedto cause additive materials to become affixed to the surface of baseparticles. More particularly, the proposed invention relates to animproved method for producing surface modifications toelectrophotographic and related toner particles.

High speed blending of dry, dispersed, or slurried particles is a commonoperation in the preparation of many industrial products. Examples ofproducts commonly made using such high-speed blending operationsinclude, without limitation, paint and colorant dispersions, pigments,varnishes, inks, pharmaceuticals, cosmetics, adhesives, food, foodcolorants, flavorings, beverages, rubber, and many plastic products. Insome industrial operations, the impacts created during such high-speedblending are used both to uniformly mix the blend media and,additionally, to cause attachment of additive chemicals to the surfaceof particles (including resin molecules or conglomerates of resins andparticles) in order to impart additional chemical, mechanical, and/orelectrostatic properties. Such attachment between particles is typicallycaused by both mechanical impaction and electrostatic bonding betweenadditives and particles as a result of the extreme pressures created byparticle/additive impacts within the blender device. Among the productswherein attachments between particles and/or resins and additiveparticles are important during at least one stage of manufacture arepaint dispersions, inks, pigments, rubber, and certain plastics.

A typical blending machine and blending tool of the prior art isexemplified in FIGS. 1 and 2. FIG. 1 is a schematic elevational view ofa blending machine 2. Blending machine 2 comprises a vessel 10 intowhich materials to be mixed and blended are added before or during theblending process. Housing base 12 supports the weight of vessel 10 andits contents. Motor 13 is located within housing base 12 such that itsdrive shaft 14 extends vertically through an aperture in housing 12.Shaft 14 also extends into vessel 10 though sealed aperture 15 locatedat the bottom of vessel 10. Shaft 14 is fitted with a locking fixture 17at its end, and blending tool 16 is rigidly attached to shaft 14 bylocking fixture 17. Before blending is commenced, lid 18 is lowered andfastened onto vessel 10 to prevent spillage. For high intensityblending, the speed of the rotating tool at its outside edge generallyexceeds 50 ft./second. The higher the speed, the more intense, and toolspeeds in excess of 90 ft./second, or 100 ft./second are common.

Turning now to FIG. 2, a perspective view of blending tool 16 of theprior art is shown. Center shank 20 has a central fixture 17A forengagement by locking fixture 17 (shown in FIG. 1). In the exampleshown, the central fixture 17A is a simple notched hole for receiving amale fixture 17 (from FIG. 1) having the same dimensions. Arrow 21 showsthe direction in which tool 16 rotates upon shaft 14. Vertical surfaces19A and 19B are fixed to the end of center shank 20 in order to increasethe surface area of the tool at its point of greatest velocity. Thisincreases the tool's “intensity”, or number of collisions per unit oftime. In addition to the surface area of the tool's face, the intensityof a tool is influenced by tool speed and the shape of the tool. Theimportance of the shape of the tool will be discussed below. Verticalsurfaces 19A and 19B combined with the leading edge of center shank 20are the surfaces of tool 16 that collide with particles mixed withinvessel 10 (shown in FIG. 1). The area through which these surfaces 19and leading edge of center shank 20 sweep during rotation of tool 16 canbe thought of as the working profile of the tool. In other words, the“profile” of a tool equals the 2-dimensional area outlined by collisionsurfaces of the tool as it sweeps through a plane that includes therotational axis of shaft 14. In FIG. 2, the space or zone immediatelybehind rotating tool 16 is labeled 22.

Various shapes and thicknesses of blending tools and collision surfacesare possible. Various configurations are shown in the brochures andcatalogues offered by manufacturer's of high-speed blending equipmentsuch as Henschel, Littleford Day Inc., and other vendors. The tool shownin FIG. 2 is based upon a tool for high intensity blending produced byLittleford Day, Inc. Among the reasons for different configurations ofblending tools are (i) different viscosities often require differentlyshaped tools to efficiently utilize the power and torque of the blendingmotor; and (ii) different blending applications require differentintensities of blending. For instance, some food processing applicationsmay require a very fine distribution of small solid particles such ascolorants and flavorings within a liquid medium. Similarly, theprocessing of snow cones requires rapid and very high intensity blendingdesigned to shatter ice cubes into small particles which are then mixedwithin the blender with flavored syrups to form a slurry.

Most high-speed blending tools of the prior art do not have raisedvertical elements such as surfaces 19 shown in FIG. 2. Instead, atypical blending tool has a collision surface formed simply by theleading edge of its central shank 20. In many tools, the leading edge isrounded or arcurately shaped in order to avoid a “snow plow” effectwherein particles become caked upon a flat leading face much as snow iscompressed and forms piles in front of a snow plow. The tool shown inFIG. 2 attempts to avoid this snow plow effect on raised collisionsurfaces 19 by slanting the forward face of surfaces 19 at an acuteangle, thereby causing particles to either bounce upward from the toolor be swept by friction upward along the face of the tool until carriedover its top and into the lee of the tool. However, a problem with thetool shown in FIG. 2 and with other tools in the prior art is that anenlarged collision surface tends to create vortices in the wake of thetool as well as to decrease the overall density of particles in the zone22 behind the tool. The degree of such density variations dependsprimarily upon the speed of the tool through the particle mixture aswell as the height, width, and depth of the collision surface 19.

Because of the above snow plow, vortex, and density limitations,conventional tools such as shown in FIG. 2 are limited both in heightand in the width of any enlarged collision surface. Indeed, it isbelieved that in tools of the prior art that have elements raised abovecenter shank 20, the height (defined below as the y-axis dimension) ofsuch vertically raised elements is less than the depth (defined below asthe z-axis dimension) of center shank 20 in its region proximate to theattachment point of the enlarged element. It is also believed that thewidth (defined below as the x-axis dimension) of any vertically raisedelement of a conventional tool has not exceeded the height, or y-axis,of center shank 20 in the region of center shank 20 proximate to wherethe raised element is attached. Lastly, it is believed that inhigh-speed blending tools of the prior art that have raised elements,the z-axis dimension, or depth, of the raised element greatly exceedsits width, or x-axis, dimension. For clarification, the height, ory-axis, dimension of a blending tool and its elements shall mean thedimension of the tool or element in the plane that contains shaft 14around which the tool rotates. The depth, or z-axis, of the tool and itselements shall mean the dimension perpendicular both to the axis of thetool's center shank and to the y-axis. The x-axis of the tool and itselements shall be measured in the direction of the axis of the tool'scenter shank. For center shank 20 itself, the x-axis dimension is ameasure of its length. For any raised collision surface, the x-axis is ameasure of its width.

Another characteristic of blending tools of the prior art is derivedfrom the above limitations upon the height of the collision surface.Specifically, as explained above, conventional tools are thin in heightand, if a vertical surface such as 19 is present, such vertical surfaceis also has a thin x-axis profile. Such thinness is required in order toavoid excessive vortices and low density regions in the lee of the tool.The trailing edges of conventional tools are sometimes rounded orarcurately shaped. However, because of the “thinness” of the tool in they-axis, it is not necessary and it is not known to arcurately shape theleading or trailing surfaces of the tool except in the region proximateto the leading and/or trailing edge.

As noted above, different mixture formulations or products often specifydifferent collision surface shapes and dimensions in order to optimizeblend efficiency, blend time, and power consumption. For instance, if afast blend process time is desired, then the blend tool can be rotatedfaster or a tool with a larger collision surface can be selected inorder to increase the number of particle collisions per unit of time, orblending intensity. However, for any given viscosity, the power andconfiguration of the blending motor effectively limits the speed of thetool and the size of a collision surface such as surface 19.

When the same blending vessel is used for different formulations orproducts requiring different tools, then procedures for changing aconventional blending tool require the following steps (described inrelation to FIG. 1) (A) lid 17 is unfastened and opened from the top ofvessel 10; (B) vessel 10 and tool 16 need to be at least partiallycleaned by vacuum and by wiping, especially in the region where blendingtool 16 is secured to shaft 14; (C) locking fixture 17 is loosened toallow unfastening of tool 16 from shaft 14; (D) blending tool 16 isdetached from the locking fixture 17; (D) blending tool 16 is liftedfrom vessel 10 with care not to bump or scratch the sides of vessel 10;(F) removed tool 16 is thoroughly cleaned before further handling and/orstorage; and (G) the preceding tasks (except cleaning) are repeated inreverse order for attachment of a different blending tool 16. For largeblender vessels that are common in many if not most industrialapplications, the weight of blending tool 16 requires a crane or hoistduring unfastening, lifting, positioning of the replacement tool, andrefastening. A human operator inside vessel 10 typically needs to helpmaneuver the crane or hoist during this process, and the combination ofpositioning a large tool while simultaneously attempting to fasten itonto shaft 14 can place the human operator in an awkward position. Evenfor smaller blenders, replacement of the tool requires fairly carefulcleaning of shaft 14 and tool 16 and often requires an awkwardmanipulation while simultaneously positioning and fastening replacementtool 16.

In addition to changing a blending tool to accommodate the requirementsof different formulations or products, blending tools may requirechanging when excessively worn. Many industrial applications requireblending of abrasive particles such as pigments, colorants (includingcarbon black), and electrophotographic toners. The above procedures forchanging a tool must be used whenever a worn tool requires replacement.

The relevance of the above description of blending tool 16 to themanufacture of electrophotographic, electrostatic or similar toners isdemonstrated by the following description of a typical tonermanufacturing process. A typical polymer based toner is produced bymelt-mixing the heated polymer resin with a colorant in an extruder,such as a Weiner Pfleider ZSK-53 or WP-28 extruder, whereby the pigmentis dispersed in the polymer. For example, the Werner Pfleiderer WP-28extruder when equipped with a 15 horesepower motor is well-suited formelt-blending the resin, colorant, and additives. This extruder has a 28mm barrel diameter and is considered semiworks-scale, running at peakthroughputs of about 3 to 12 lbs./hour.

Toner colorants are particulate pigments or, alternatively, are dyes.Numerous colorants can be used in this process, including but notlimited to:

Pigment Pigment Brand Name Manufacturer Color Index Permanent Yellow DHGHoechst Yellow 12 Permanent Yellow GR Hoechst Yellow 13 Permanent YellowG Hoechst Yellow 14 Permanent Yellow NCG-71 Hoechst Yellow 16 PermanentYellow NCG-71 Hoechst Yellow 16 Permanent Yellow GG Hoechst Yellow 17Hansa Yellow RA Hoechst Yellow 73 Hansa Brilliant Yellow 5GX-02 HoechstYellow 74 Dalamar .RTM. Yellow TY-858-D Heubach Yellow 74 Hansa Yellow XHoechst Yellow 75 Novoperm .RTM. Yellow HR Hoechst Yellow 75 Cromophtal.RTM. Yellow 3G Ciba-Geigy Yellow 93 Cromophtal .RTM. Yellow GRCiba-Geigy Yellow 95 Novoperm .RTM. Yellow FGL Hoechst Yellow 97 HansaBrilliant Yellow 10GX Hoechst Yellow 98 Lumogen .RTM. Light Yellow BASFYellow 110 Permanent Yellow G3R-01 Hoechst Yellow 114 Cromophtal .RTM.Yellow 8G Ciba-Geigy Yellow 128 Irgazin .RTM. Yellow 5GT Ciba-GeigyYellow 129 Hostaperm .RTM. Yellow H4G Hoechst Yellow 151 Hostaperm .RTM.Yellow H3G Hoechst Yellow 154 L74-1357 Yellow Sun Chem. L75-1331 YellowSun Chem. L75-2377 Yellow Sun Chem. Hostaperm .RTM. Orange GR HoechstOrange 43 Paliogen .RTM. Orange BASF Orange 51 Irgalite .RTM. 4BLCiba-Geigy Red 57:1 Fanal Pink BASF Red 81 Quindo .RTM. Magenta MobayRed 122 Indofast .RTM. Brilliant Scarlet Mobay Red 123 Hostaperm .RTM.Scarlet GO Hoechst Red 168 Permanent Rubine F6B Hoechst Red 184Monastral .RTM. Magenta Ciba-Geigy Red 202 Monastral .RTM. ScarletCiba-Geigy Red 207 Heliogen .RTM. Blue L 6901F BASF Blue 15:2 Heliogen.RTM. Blue NBD 7010 BASF Heliogen .RTM. Blue K 7090 BASF Blue 15:3Heliogen .RTM. Blue K 7090 BASF Blue 15:3 Paliogen .RTM. Blue L 6470BASF Blue 60 Heliogen .RTM. Green K 8683 BASF Green 7 Heliogen .RTM.Green L 9140 BASF Green 36 Monastral .RTM. Violet R Ciba-Geigy Violet 19Monastral .RTM. Red B Ciba-Geigy Violet 19 Quindo .RTM. Red R6700 MobayQuindo .RTM. Red R6713 Mobay Indofast .RTM. Violet Mobay Violet 23Monastral .RTM. Violet Maroon B Ciba-Geigy Violet 42 Sterling .RTM. NSBlack Cabot Black 7 Sterling .RTM. NSX 76 Cabot Tipure .RTM. R-101DuPont Mogul L Cabot BK 8200 Black Toner Paul Uhlich

Any suitable toner resin can be mixed with the colorant by thedownstream injection of the colorant dispersion. Examples of suitabletoner resins which can be used include but are not limited topolyamides, epoxies, diolefins, polyesters, polyurethanes, vinyl resinsand polymeric esterification products of a dicarboxylic acid and a diolcomprising a diphenol. Any suitable vinyl resin may be selected for thetoner resins of the present application, including homopolymers orcopolymers of two or more vinyl monomers. Typical vinyl monomeric unitsinclude: styrene, p-chlorostyrene, vinyl naphthalene, unsaturatedmonoolefins such as ethylene, propylene, butylene, and isobutylene;vinyl halides such as vinyl chloride, vinyl bromide, vinyl fluoride,vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate, and thelike; vinyl esters such as esters of monocarboxylic acids includingmethyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethylacrylate, phenyl acrylate, methylalphachloroacrylate, methylmethacrylate, ethyl methacrylate, and butyl methacrylate; acrylonitrile,methacrylonitrile, acrylimide; vinyl ethers such as vinyl methyl ether,vinyl isobutyl ether, vinyl ethyl ether, and the like; vinyl ketonessuch as vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenylketone and the like; vinylidene halides such as vinylidene chloride,vinylidene chlorofluoride and the like; and N-vinyl indole, N-vinylpyrrolidene and the like; styrene butadiene copolymers, Pliolites,available from Goodyear Company, and mixtures thereof.

The resin or resins are generally present in the resin-toner mixture inan amount of from about 50 percent to about 100 percent by weight of thetoner composition, and preferably from about 80 percent to about 100percent by weight.

Additional “internal” components of the toner may be added to the resinprior to mixing the toner with the additive. Alternatively, thesecomponents may be added during extrusion. Various known suitableeffective charge control additives can be incorporated into tonercompositions, such as quaternary ammonium compounds and alkyl pyridiniumcompounds, including cetyl pyridinium halides and cetyl pyridiniumtetrafluoroborates, as disclosed in U.S. Pat. No. 4,298,672, thedisclosure of which is totally incorporated herein by reference,distearyl dimethyl ammonium methyl sulfate, and the like. Particularlypreferred as a charge control agent is cetyl pyridinium chloride. Theinternal charge enhancing additives are usually present in the finaltoner composition in an amount of from about 1 percent by weight toabout 20 percent by weight.

After the resin, colorants, and internal additives have been extruded,the resin mixture is reduced in size by any suitable method includingthose known in the art. Such reduction is aided by the brittleness ofmost toners which causes the resin to fracture when impacted. Thisallows rapid particle size reduction in pulverizers or attritors such asmedia mills, jet mills, hammer mills, or similar devices. An example ofa suitable hammer mill is an Alpine RTM Hammer Mill. Such a hammer millis capable of reducing typical toner particles to a size of about 10microns to about 30 microns. For color toners, toner particle sizes mayaverage within an even smaller range of 4-10 microns.

After reduction of particle size by grinding or pulverizing, aclassification process sorts the particles according to size. Particlesclassified as too large are typically fed back into the grinder orpulverizer for further reduction. Particles within the accepted rangeare passed onto the next toner manufacturing process.

After classification, the next typical process is a high speed blendingprocess wherein surface additive particles are mixed with the classifiedtoner particles within a high speed blender. These additives include butare not limited to stabilizers, waxes, flow agents, other toners andcharge control additives. Specific additives suitable for use in tonersinclude fumed silica, silicon derivatives such as Aerosil.RTM. R972,available from Degussa, Inc., ferric oxide, hydroxy terminatedpolyethylenes such as Unilin RTM., polyolefin waxes, which preferablyare low molecular weight materials, including those with a molecularweight of from about 1,000 to about 20,000, and including polyethylenesand polypropylenes, polymethylmethacrylate, zinc stearate, chromiumoxide, aluminum oxide, titanium oxide, stearic acid, and polyvinylidenefluorides such as Kynar. In aggregate these additives are typicallypresent in amounts of from about 0.1 to about 1 percent by weight oftoner particles. More specifically, zinc stearate shall preferably bepresent in an amount of from about 0.4 to about 0.6 weight percent.Similar amounts of Aerosi.RTM. is preferred. For proper attachment andfunctionality, typical additive particle sizes range from 5 nanometersto 50 nanometers. Some newer toners require a greater number of additiveparticles than prior toners as well as a greater proportion of additivesin the 25-50 nanometer range. When combined with smaller toner particlesizes required by color toners, the increased size and coverage ofadditive particles for some color toners creates increased need for highintensity blending.

The amount of external additives is measured in terms of percentage byweight of the toner composition, and the additives themselves are notincluded when calculating the percentage composition of the toner. Forexample, a toner composition containing a resin, a colorant, and anexternal additive may comprise 80 percent by weight resin and 20 percentby weight colorant. The amount of external additive present is reportedin terms of its percent by weight of the combined resin and colorant.

The above additives are typically added to the pulverized tonerparticles in a high speed blender such as a Henschel Blender FM-10, 75or 600 blender. The high intensity blending serves to break additiveagglomerates into the appropriate nanometer size, evenly distribute thesmallest possible additive particles within the toner batch, and attachthe smaller additive particles to toner particles. Each of theseprocesses occurs concurrently within the blender. Additive particlesbecome attached to the surface of the pulverized toner particles duringcollisions between particles and between particles and the blending toolas it rotates. It is believed that such attachment between tonerparticles and surface additives occurs due to both mechanical impactionand electrostatic attractions. The amount of such attachments isproportional to the intensity level of blending which, in turn, is afunction of both the speed and shape (particularly size) of the blendingtool. The amount of time used for the blending process plus theintensity determines how much energy is applied during the blendingprocess. For this purpose, “intensity” means the number of particlecollisions per unit of time. For an efficient blending tool that avoidssnow plowing and excessive vortices and low density regions, “intensity”can be effectively measured by reference to the power per unit mass(typically expressed as W/lb) of the blending motor driving the blendingtool. Using a standard Henschel Blender tool to manufacture conventionaltoners, the blending times typically range from one (1) minute to twenty(20) minutes per typical bath of 60-1000 kilograms. For certain morerecent toners such as toners for Xerox Docucenter 265 and relatedmultifunctional printers, blending speed and times are increased inorder to assure the multiple layers of surface additives become attachedto the toner particles. Additionally, for those toners that require agreater proportion of additive particles in excess of 25 nanometers,more blending speed and time is required to force the larger additivesinto the base resin particles.

The process of manufacturing toners is completed by a screening processto remove toner agglomerates and other large debris. Such screeningoperation may typically be performed using a Sweco Turbo screen set to37 to 105 micron openings.

The above description of a process to manufacture an electrophotographictoner may be varied depending upon the requirements of particulartoners. In particular, for full process color printing, colorantstypically comprise yellow, cyan, magenta, and black colorants added toseparate dispersions for each color toner. Colored toner typicallycomprises much smaller particle size than black toner, in the order of4-10 microns. The smaller particle size makes the manufacturing of thetoner more difficult with regard to material handling, classificationand blending.

The above general description of a process for makingelectrophotographic toners is well known in the art. More informationconcerning methods and apparatus for manufacture of toner are availablein the following U.S. patents, and each of the disclosures of which areincorporated herein: U.S. Pat. No. 4,338,380 issued to Erickson, et al;U.S. Pat. No. 4,298,672 issued to Chin; U.S. Pat. No. 3,944,493 issuedto Jadwin; U.S. Pat. No. 4,007,293 issued to Mincer, et al; U.S. Pat.No. 4,054,465 issued to Ziobrowski; U.S. Pat. No. 4,079,014 issued toBurness, et al; U.S. Pat. No. 4,394,430 issued to Jadwin, et al; U.S.Pat. No. 4,433,040 issued to Niimura, et al; U.S. Pat. No. 4,845,003issued to Kiriu, et al; U.S. Pat. No. 4,894,308 issued to Mahabadi etal.; U.S. Pat. No. 4,937,157 issued to Haack, et al; U.S. Pat. No.4,937,439 issued to Chang et al.; U.S. Pat. No. 5,370,962 issued toAnderson, et al; U.S. Pat. No. 5,624,079 issued to Higuchi et al.; U.S.Pat. No. 5,716,751 issued to Bertrand et al.; U.S. Pat. No. 5,763,132issued to Ott et al.; U.S. Pat. No. 5,874,034 issued to Proper et al.;and U.S. Pat. No. 5,998,079 issued to Tompson et al.

As described above, the process of blending plays an increasinglyimportant role in the manufacture of electrophotographic and similartoners. It would be advantageous if an apparatus and method were foundto accelerate the blending process and to thereby diminish the time andcost required for blending. Similarly, since different formulations andproducts often require different blending speed and intensities, itwould be advantageous if an apparatus and method were found to allow asingle blending tool to be reconfigured in situ for various blendingintensities rather than requiring cleaning, removal, and replacement ofthe entire blending tool for each required change in intensity. Lastly,it would be advantageous to create an improved toner having a greaterquantity of surface additives than heretofore manufactured and havingsuch additives adhere to toner particles with greater force thanheretofore manufactured.

SUMMARY OF THE INVENTION

One aspect of the present invention is an improved toner, comprising: acolorant; a toner resin mixed with the colorant, wherein each combinedresin and colorant particle has an average size greater than 4 microns;and surface additive particles averaging greater than 30 nanometers insize, wherein the amount of such surface additives average greater thantwo (2) percent of the combined weight of resin and colorant in thetoner. Another aspect of the present invention is an improved toner madeby an improved process, comprising: mixing a toner resin and a colorant;extruding the resin and colorant mixture; attriting the resin andcolorant mixture; classifying the attrited particles into particlesaveraging 4 to 10 micron in size; and blending sufficient surfaceadditive particles and the classified particles in a high intensityblender for at least 10 minutes such that the weight of attached surfaceadditives is greater than four (4) of the weight of the classifiedparticles.

Yet another aspect of the present invention is an improved process formaking toners, comprising mixing a toner resin and a colorant;

extruding the resin and colorant mixture; attriting the resin andcolorant mixture; classifying the attrited particles into particlesaveraging 4 to 10 micron in size; and blending sufficient surfaceadditive particles and the classified particles in a high intensityblender for at least 10 minutes such that the weight of attached surfaceadditives is greater than three (3) percent of the weight of theclassified particles.

BRIEF DESCRIPTION OF THE DRAWINGS

Other aspects of the present invention will become apparent as thefollowing description proceeds and upon reference to the drawings, inwhich:

FIG. 1 is a schematic elevational view of a blending machine of theprior art;

FIG. 2 is a perspective view of a blending tool of the prior art;

FIG. 3 is a perspective view of an embodiment of the blending tool ofthe present invention;

FIG. 4 is a perspective view of an embodiment of the blending tool ofthe present invention having an adjustable articulator hinge;

FIG. 5 is a perspective view of an embodiment of an articulator hinge ofthe present invention; and

FIG. 6 is a chart showing specific power levels of the blending motorwhen using different configurations of the blending tool of the presentinvention and when using a conventional tool of the prior art.

FIG. 7 is a chart showing AAFD Percent values for toners comprisingvarious quantities of surface additives blended at different blendingintensities.

DETAILED DESCRIPTION OF THE DRAWINGS

While the present invention will hereinafter be described in connectionwith its preferred embodiments and methods of use, it will be understoodthat it is not intended to limit the invention to these embodiments andmethod of use. On the contrary, the following description is intended tocover all alternatives, modifications, and equivalents, as may beincluded within the spirit and scope of the invention as defined by theappended claims.

One aspect of the present invention is creation of a blending toolcapable of generating more intensity (collisions/unit of time) thanheretofore possible. This increased intensity is the result of anenlarged collision surface employing an aerodynamic-like shape thatenables enlargement of the collision profile while minimizing vorticesand particle voids in the zone behind the rotating blending tool. Thecombination of a larger collision profile and minimization of voids andvortices behind the tool result in more collisions per unit of time, orintensity. Such increase of intensity allows blending time to bedecreased, thereby saving batch costs and increasing productivity.

Accordingly, a blending tool 50 of the present invention is shown inFIG. 3 inside a vessel 10 that is similar to that shown in FIG. 1 above.Center shank 51 contains locking fixture 52 at its middle for mountingonto rotating drive shaft 14 (not shown) of the blending machine 2 (notshown). As shown in FIG. 3, an enlarged collision element comprisescollision anvil 55 that is proportionately larger than the collisionsurface of blending tools of the prior art such as that shown in FIG. 2.In conventional tools, as discussed above, enlarged collision surfacesare not practical because a large collision surface creates too much“snow plow” compaction in front of the tool and vortices and relativevoids in the wake of the tool. To overcome these impediments, a novelfeature of the present invention is an enlarged collision element suchas collision anvil 55 with cross-sectional perimeters of its leewardsurfaces that decrease as such cross-sections are measured closer to thetrailing edge of the tool, i.e., its sides and/or top and bottomsurfaces tend towards convergence toward the trailing edge. This“negative slope” of the leeward surface increases intensity sinceparticles that are pushed upward or sideways upon contact with thecollision anvil slide along the leeward slope of the tool to fill itswake as the tool slides through the particle mixture. Although theactual movements of particles within a blending machine requires complex3-dimensional analysis, it is believed that an arcuate shape bestaccomplishes the above design since it causes collision anvil 55 tofunction much like an air foil in a gas fluid. In other words, theparticle media through which the blending tool moves acts like a fluidas it is mixed by the tool. As with an air foil, the sloping leewardshape helps minimize voids and turbulence behind the tool. The result isgreater particle density available for collision by the next arm of thetool as it sweeps through the blending zone. Greater density ofparticles leads to grater intensity (collisions/unit of time).Additionally, as noted above, the rounded shape of the leading profileof collision anvil 55 results in more flow of particles over the tooland less “snow plow” compaction in front of the tool. The result is thatfor the same consumption of power by the blending machine, it isbelieved that the present invention allows either greater tool speed ora larger collision plate profile. Either greater speed or larger profileresult in greater blend intensity.

For clarity, the portion of collision anvil 55 that adds to the profileof the tool can be considered its “leading surface” and is labeled 57 inFIG. 3. This is the surface that most directly impacts the particlemedia. The portion of collision anvil 55 to the rear of the leadingsurface can be considered its “trailing surface” and is labeled 56 inFIG. 3. Using the arcurately shaped trailing surface of the presentinvention, it is possible to increase the height, or y-axis dimension,of the collision anvil to exceed (even by a factor greater than 2 or 3)the depth, or z-axis dimension, of center shank 51 in the regionproximate to where collision anvil 55 is attached. It is also possibleto increase the width, or x-axis dimension, of collision anvil 55 to awidth that exceeds (even by a factor greater than 1.5 or 2) the height,or y-axis, of center shank 51 in the region of center shank 51 proximateto where collision plate 35 is attached. For a large collision anvil 55,it is preferred that collision anvil 55 be hollow or comprised of arelatively thin plate in order to reduce its weight. Specifically, it ispreferable that the leading surface of collision anvil 55 or otherenlarged collision element of the present invention be less thanone-half inch thick and preferably as thin as 3/16 inch thick.

It should be recognized that application of the above design principlesenables any number of designs, including the design discussed belowrelating to use of adjustable and spaced apart collision plates.Although the preferred embodiment of this aspect of the inventioncomprises an arcurate shape over the entire trailing and leadingsurfaces, it may be possible to achieve an acceptable result using anegative slope over less than all (perhaps approximately one-half) ofthe entire trailing surface. It also preferred that most or all of theleading surface have an arcurate shape. The larger the profile of thecollision surface, the larger the proportion of the trailing surfacethat must be negatively sloped in order to achieve the effects of thepresent invention.

Yet another aspect of the present invention is a blending tool thatallows reconfiguration of the effective collision surface size andprofile without removal of the entire tool. Referring to FIG. 4,blending tool 30 comprises a center shank 31 and collision plates 35Aand 35B. Center shank 31 contains locking fixture 32 at its middle formounting onto rotating drive shaft 14 (not shown) of the blendingmachine 2 (not shown). Each end of center shank 31 contains a connectingmechanism 33 for rigidly mounting and holding an arm 34. Connectingmechanism 33 shown in FIG. 4 comprises a simple nut and bolt fastenerwhich compresses together and rigidly positions collision plates 35A and35B on arms 34A and 34B and on center shank 31, respectively. As will bedescribed more fully below, below, different arrangements forpositioning arms 34A and 34B are possible. Additionally, differentarrangements for an adjustable collision surface are possible. Forinstance, each end region of the center shank 31 could comprise aleading edge flap connected to the center shank by one, two, or moreconnector mechanisms such that the angle of the flaps could be tilteddown or raised much like the leading edge slat of some high speed jetsand airplanes

In the embodiment shown, mounted at the opposite end of arm 34A frommechanism 33 is an enlarged collision surface formed out of a collisionplate 35A. Collision plate 35A differs from collision surfaces of theprior art since collision plate 35A is spaced apart and not integrallyforged, welded, or otherwise formed as part of center shank 31.Additionally, collision plate 35A presents a substantially largerprofile than the profile of center shank 31. Different arrangements forlocking collision plate 35A into position are possible. For instance,collision plate 35A could be directly connected to center shank 31without an arm 34A therebetween or arm 34A could be permanently attachedto center shank 31 with a connecting mechanism between the arm 34A andcollision plate 35A. Arm 34A can assume any number of embodiments,including compound elements, as long as arm 34A functions to positionthe collision plate apart from center shank 31. A preferred embodimentof the present invention uses a connecting mechanism such as mechanism33 that enables removal and replacement of a collision plate when thecollision plate reaches the end of its useful life due to abrasion andwear. Without such removable collision plates, the entire blending toolrequires disposal or remanufacturing when the collision plate reachesthe end of its useful life.

Connecting mechanism 33 can assume any number of arrangements long as itallows adjustment of the profile of the tool. In the embodiment shown,mechanism 33 allows arm 34A to pivot about the axis of center shank 31.In effect, mechanism 33 forms an articulator hinge that allows arm 34Ato assume any number of angles in relation to center shank 31. Thisarticulator hinge is a simple bolt and nut fastener that can be loosenedand tightened with standard tools such as socket wrenches. Any number ofother articulator hinges are possible as long as they allow arm 34A topivot when the hinge is loosened and to be held rigidly in place oncethe hinge is tightened.

An example of an alternate embodiment of an articulator hinge 33 isshown in FIG. 5. The embodiment shown in FIG. 5 allows articulation ofarm 34 into pre-set positions determined by alignment of bolt 45 (whichruns through hole 46 in arm 34) with bored holes 41, 42, 43, and 44formed in central hub 35. The process of articulating the hinge to thesepre-set angles is accomplished by the relatively easy loosening andwithdrawal bolt 45. As bolt 45 becomes withdrawn, arm 34 can berepositioned such that bolt 45 aligns with and can be inserted into oneof alternate holes 41, 42, 43, and 44. Lastly, arm 34 is again securedin place by refastening bolt 45.

It should be recognized that may alternate designs for reconfigurabletools are possible. For instance, the above description of a leadingedge flap could accomplish this purpose. Similarly, a movable collisionsurface, preferably a collision plate, could be connected directly tothe center shank without an arm to provide spaced apart separationbetween the surface and the center shank. Although many such variationsare possible, however, the preferred embodiment comprises an arm and aspaced apart collision plate as described above in relation to FIGS. 3and 4.

The advantages of the reconfigurable blending tool of the presentinvention is made clear when the adjustment procedures are compared tothe procedures necessary to changeout the non-adjustable tooling of theprior art. The conventional procedures are described above and require,among other steps, cleaning of the blending vessel and tool to gainaccess to the lock mechanism of the drive shaft of the blending machinefollowed by typical use of a crane or hoist to lift the tool out of thevessel. In contrast, the comparable process for altering theconfiguration of the blending tool of the present invention is asfollows (numbers are in reference to FIG. 1 and FIG. 3, as applicable):(A) lid 17 is unfastened and opened from the top of vessel 10; (B)blending tool 16 needs to be at least partially cleaned by vacuum and bywiping in the region of articulator hinge 33; (C) articulator hinge 33is loosened to allow arm 34 (and therefore collision plate 35) to berepositioned; (D) arm 34 is repositioned to the new angle required bythe next formulation or product; (D) articulator hinge 33 isre-tightened.

In sum, blending tool 16 of the present with its articulator hingeenables significant time, safety, and productivity savings. Among theadvantages are: 1) elimination of the need for a crane or hoist, therebysaving time (especially if such crane or hoist is not immediatelyavailable) as well as a requirement for expensive supplementaryequipment such as a hoist; 2) human operators do not need tosimultaneously position and fasten during removal of the old tools andplacement of the new tool; and 3) cleaning tasks are greatly curtailedand simplified since the entire tool need not be cleaned forreplacement, handling, or storage. Cleaning of vessel 10 is alsolessened and shaft 14 need not be cleaned at all. Lastly, it isobviously less expensive to be able to use a single flexible blendingtool for various formulations and products than to require an inventoryof tools which must be substituted each time a formulation or productrequires a different tool configuration.

The flexibility of the blending tool of the present invention isdemonstrated in FIG. 6, which shows the various levels of intensity thatwere obtained with the tool of the present invention as it isreconfigured into different positions. Each of the 4 curves shown onFIG. 5 show data created during blending of Xerox toner for a XeroxDocucenter 265 multifunctional printer in a Henschel 75-liter blender.Four blends were made, all using the same tool speed. The vertical axismeasures the specific power of the blending motor (W/lb) which, asdiscussed above, is considered a good measure of the blend intensitywhen using an efficient blending tool. The horizontal axis measures timeof the blend. The curve marked with round data points shows the resultswith arm 34 set at 45 degrees, which angle offered the greatest toolprofile for this experiment. As can be seen in FIG. 6, this curve withsquare data, reflecting the largest profile, shows the greatest blendintensity. The curve marked with diamond data points shows the resultswith arm 34 set at 22.5 degrees, while the curve marked with triangulardata points shows the results with arm 34 set at 0 degrees. These anglescause decreasing tool profiles and, as expected, decreasing blendintensity that reflects the decreased profiles. Lastly, the curve withsquare shaped data points shows the results using a standard Henschelblending tool typically used when blending electrophotographic toners(this tool differs from the tool in FIG. 2). When compared to theresults using the 45-degree arm position, the standard tool providedless than 50% of the blend intensity offered by the tool of the presentinvention at its maximum profile and intensity. Such results are to beexpected since conventional tools lack both collision plates and arcuatetrailing surfaces.

Yet another aspect of the present invention is an improved toner with agreater quantity of surface additives and with greater adhesion of theseadditive particles to the toner particles. As discussed above, newercolor toner particles are in the range of 6-10 microns, which is smallerthan previous monochrome toner particles. Additionally, whereas priorart toners typically have surface additives attached to toner particlesat less than 1% weight percent, newer color toners require more robustflow aids, charge control, and other qualities contributed by surfaceadditives. Accordingly, the size of surface additive particles isdesired to be increased into the 30 to 50 nanometer range. Thecombination of smaller toner particles and larger surface additiveparticles makes attachment of increased amounts of additives moredifficult.

In order to measure the adhesive force of surface additives to tonerparticles, a measurement technique is required. Such a technique isdisclosed in patent applications titled “Method for Additive AdhesionForce Particle Analysis and Apparatus Thereof”, U.S. Ser. No.09/680,066, filed on Oct. 5, 2000, and “Method for Additive AdhesionForce Particle Analysis and Apparatus Thereof”, U.S. Ser. No.09/680,048, filed on Oct. 5, 2000. The technique taught in suchapplications yields a value known as an “Additive Adhesion ForceDistribution” (“AAFD”) value. Both applications are hereby incorporatedby reference. In effect, AAFD value is a measure of how well a surfaceadditive sticks to a toner particle even after being blasted withintense sonic energy. As specifically applied to the improved tonersherein, the AAFD measurement technique comprises the following:

Stage 1—Stirring

-   1. Weigh approx. 2.6 g toner into 100 ml Beaker-   2. Add 40 ml 0.4% Triton-X solution-   3. Stir for 5 min. in 4 station automated stirrer (Start at 20K rpm,    slowly increase to 30K-40K-50K rpm)-   4. Check for non-wetted particles, re-stir if necessary.    Stage 2—Sonification (4 horn setup)-   1. Sonify at 3 kJ, 6 kJ and 12 kJ in sonifier model Sonica Vibra    Cell Model VCX 750 made by Sonics and Materials, Inc. using four (4)    ⅝ inch horns at frequency of 19.95 kHz.-   2. Horns are matched and calibrated for each energy level. For 3 kJ,    the time is 2.5 to 3.0 minutes; for 6 kJ, time is 5.0 to 6.0    minutes; and for 12 kJ, time is 10.0-12.0 minutes.-   3. Horn should be 2 mm from beaker bottom.-   4. Transfer to labeled disposable 50 ml Centrifuge Tube (Pour ½ in,    swirl, pour remainder in, add distilled water to bring solution to    45 ml.)-   5. Centrifuge immediately    Stage 3—Centrifuging-   1. Centrifuge at 2000 rpm for 3 min.-   2. Decant supernatant liquid, add 40 ml distilled water, shake well.    (add 10 ml Triton-X solution if necessary)-   3. Centrifuge at 2000 rpm for 3 min.-   4. Decant supernatant liquid, add 40 ml DI, shake well-   5. Centrifuge at 2000 rpm for 3 min.-   6. Decant supernatant liquid, add very small amount of distilled    water. Re-disperse w/spatula.    Stage 4—Filtering-   1. Turn on filtration machine with wet Whatman #5 Filter-   2. Rinse spatula with distilled water onto filter center; pour rinse    slowly into center of filter; rinse 1 or 2 times with squirt of    distilled water; pour rinse onto filter slowly, rinse with 10 ml    distilled water; pour rinse onto filter-   3. turn off filter machine-   4. Remove filter and dry overnight on top of oven in hood.    Stage 5—Grinding/Pellet Press-   1. Transfer Toner to weighing paper by turning filter over and    tapping filter with spatula without scraping filter.-   2. Curl weighing paper and pour sample into plastic grinder    container.-   3. Grind for 4-5 min.-   4. Press into pellets    Stage 6—Compute AAFD Value    Analyze by Wavelength Dispersive X-Ray Fluorescence Spectroscopy    (WDXRF) to compare percent of remaining surface additives    (particularly SiO2 and TiO2) to percent of additives in non-sonified    control pellets. The ratio equals the AAFD value expressed as a    percent. WDXRF works because each additive such as SiO2 can be    detected by its characteristic frequency.

A series of Pareto analyses confirms that when AAFD values are computedfor variations of blend intensity, blend energy (speed of tool), andamount of additives, the factor that most influences AAFD values isblend intensity. The second ranking factor is minimization of the amountof additives present. However, as discussed above, a goal of theimproved toner of the present invention is both an increase in adhesionand an increase in the total quantity of additives. As such, an improvedblending tool offering increased blend intensity is a prime factor inachieving the improved toner of the present invention.

A second set of Pareto analyses corroborates the importance of blendintensities and the relevance of AAFD values. In the second set ofanalyses, the ability of toner particles to flow easily without stickingtogether was measured in relation to blend intensity, blend energy, andthe total quantity of additives. Certain surface additives such assilica are added to toner particles to ameliorate this tendency to sticktogether, or “cohesion”, of toner particles. In the second set of Paretoanalyses, blend intensity is again found to be the most significantfactor in ameliorating the cohesion tendency of toners. The second mostimportant factor is the quantity of additive particles. This is notsurprising since the characteristic of certain additive particles is todecrease cohesion forces.

It is believed that blend intensity is the most important factor forAAFD values and for minimization of cohesion between toner particlesboth because blend intensity leads to greater mechanical andelectrostatic adhesion between surface additive particles and tonerparticles and because the greater the blend intensity, the more even thedistribution of additive particles around the surface of tonerparticles.

Turning now to FIG. 7, a series of AAFD value curves are presented forvarious blend intensities and quantities of surface additives (by wt. %)when blended for less than 10 minutes. For each curve, the size of tonerparticles ranged from 4 to 10 microns, and the size of surface additivesranged from 30 to 40 nanometers. The results were as follows:

-   -   1) The curve with square data points shows AAFD values for        conventional toners of the prior art having one (1) percent by        weight surface additives using a conventional blending tool.        Such conventional blending tools used for toners do not have        raised collision surfaces as shown in FIG. 2 or as disclosed in        the present invention. The 3 KJ value is estimated.    -   2) The curve with square-surrounding-circle data pints shows        values for toners having four (4) percent by weight surface        additives using a conventional blending tool used for        manufacture of toners. The 3 KJ value is estimated.    -   3) The curve with round data points shows approximated AAFD        values for toners having one (1) percent by weight surface        additives using high intensity blending achieved with an        enlarged collision surface.    -   4) The curve with triangular data points shows approximated AAFD        values for toners having two (2) percent by weight surface        additives using high intensity blending achieved with an        enlarged collision surface.    -   5) The curve with oval data points shows approximated AAFD        values for toners having three (3) percent by weight surface        additives using high intensity blending achieved with an        enlarged collision surface.    -   6) The curve with diamond data points shows AAFD values for        toners having at least four (4) percent by weight surface        additives using high intensity blending achieved with an        enlarged collision surface of the present invention.

The results are consistent with the above described Pareto analyses.Specifically, where blending is most intense and the quantity of surfaceadditives is smallest (the curve with round data points), then the AAFDvalues are highest. Where blend intensity is least but surface additivequantities are greatest (the square-surrounding-circle data points),then AAFD values are lowest. Since both high AAFD values and highquantities of surface additives are desired, then a preferred embodimentof the improved toner made using high intensity blending is representedby the curve with diamond data points, i.e. a toner comprising 4 to 10micron toner particles having greater than 4 percent by weight ofsurface additives that average more than 30 nanometers, such toneryielding AAFD values in excess of 40 percent after 10 minutes ofsonification at 12 kJ of energy. Such high additive quantities and highAAFD values are achievable using the high intensity blending of thepresent invention.

In summary, the blending tool of the present invention includes acollision plate, arcurate surfaces, and articulator hinge. When comparedto known blending tools in the prior art, the present invention permitshigher blend intensity than heretofore possible without snow plowcompaction in front of the tool or vortices and voids in the wake of thetool. Additionally, the articulator hinge of the present inventionenable a single blending tool of the present invention to assume a widevariety of different configurations, each enabling a different level ofblend intensity as may be required by different formulations andproducts. Together, these improvements of the present invention enablegreater blend intensity and overall productivity as well as savings intool and inventory cost, time, and safety. When these advantages areapplied to the manufacture of toners, substantial cost savings result.Moreover, the high intensity blending of the present invention yields animproved toner composition having greater quantities of surfaceadditives than heretofore known and with greater adhesion betweensurface additives and toner particles.

It is, therefore, evident that there has been provided in accordancewith the present invention a blending tool and toner particles thatfully satisfies the aims and advantages set forth above. While theinvention has been described in conjunction with several embodiments, itis evident that many alternatives, modifications, and variations will beapparent to those skilled in the art. Accordingly, it is intended toembrace all such alternatives, modifications, and variations as fallwithin the spirit and broad scope of the appended claims.

1. A toner, comprising: (a) a colorant; (b) a toner resin mixed with thecolorant, wherein each combined resin and colorant particle has anaverage diameter size of equal from 4 to or less than about 10 microns;and (c) surface additive particles averaging less than about 40nanometers in having an average particle diameter size of from 30 to 40nanometers, wherein the amount of such surface additives average equalto or greater than about two (2) percent of the combined weight of resinand colorant in the toner and wherein the Additive Adhesion ForceDistribution percent value after 12 kilojoules of energy is greater than40 percent.
 2. The toner of claim 1, wherein the toner resin furthercomprises internal additives.
 3. The toner of claim 1, wherein thecombined resin and colorant composite has an average diameter size inthe range of about 4 to about 10 microns.
 4. The toner of claim 1,wherein the amount of surface additives average greater than about three(3) percent of the combined weight of resin and colorant in the toner.5. The toner of claim 1, wherein the amount of surface additives averagegreater than about four (4) percent of the combined weight of resin andcolorant in the toner.
 6. The toner of claim 1, wherein the AdditiveAdhesion Force Distribution value percent value after 10 minutes ofsonification and 12 kilojoules of energy is greater than 40 percent. 7.The improved toner of claim 6, the AAFD percent value is measured ontoners blended for less than 10 minutes.
 8. The toner of claim 1,wherein the Additive Adhesion Force Distribution percent values wereobtained using four (4) ⅝ inch horns emitting at a frequency of 19.95kilohertz from a distance of approximately 2 mm.
 9. The toner of claim1, wherein the toner is blended for less than 10 minutes.
 10. The tonerof claim 1, wherein the Additive Adhesion Force Distribution percentvalue after 6 kilojoules of energy is greater than 60 percent.
 11. Thetoner of claim 1, wherein the Additive Adhesion Force Distributionpercent value after 3 kilojoules of energy is greater than 80 percent.12. The claim 1, wherein: (a) the combined resin and colorant compositehas an average size in the range of about 4 to about 10 microns; and (b)the surface additive particles average between 30 and 50 nanometers indiameter size and wherein the amount of such surface additives averagegreater than four (4) percent of the combined weight of resin andcolorant in the toner.
 13. The toner of claim 12, wherein the AdditiveAdhesion force Distribution percent values were obtained using four (4)5/8 inch horns emitting at a frequency of 19.95 kHz from a distance ofapproximately 2 mm.
 14. The toner of claim 12, wherein the AdditiveAdhesion Force Distribution percent value after 6 kJ of energy isgreater than 60 percent.
 15. An toner made by an improved a process,comprising: (a) mixing a toner resin and a colorant; (b) extruding theresin and colorant mixture; (c) attriting the resin and colorantmixture; (d) classifying the attrited particles into particles averagingabout 4 to about 10 micron in size; and (e) blending sufficient surfaceadditive particles and the classified particles in a high intensityblender for at least 10 minutes such that the weight of surfaceadditives that become attached is greater than three (3) percent of theweight of the classified particles.
 16. The toner of claim 15, whereinthe weight of attached surface additives is greater than four (4)percent of the weight of the classified particles.
 17. The toner ofclaim 15, wherein the blending is intense enough to yield AdditiveAdhesion Force Distribution percent values after 12 kJ of energy greaterthan 40 percent.
 18. The toner of claim 15, wherein the blending isintense enough to yield Additive Adhesion Force Distribution percentvalues after 6 kJ of energy greater than 60 percent.
 19. The toner ofclaim 1, wherein the average diameter size of the surface additiveparticles is greater than about 30 nanometers.